Method and apparatus for circularly magnetizing a helical conductive rod

ABSTRACT

A method and apparatus for circularly magnetizing a helical rod wherein an insulating sheath is placed over the rod and a conductive sheath is placed over the insulation, the conductive sheath being in the form of a braided wire tube or the like. At one end of the rod, the rod and the tube are conductively connected. At the other end of the rod, the rod and the tube are both connected to a DC source to pass a direct current through the rod and the conductive tube.

1451 Dec. 16, 1975 United States Patent 1191 Garshelis METHOD AND APPARATUS FOR 3,488,587 1/1970 324/47 CIR ULA MAGNETIZING A HELICAL 3 703,681 11/1972 Johnson et 324/43 CONDUCTIVE ROD FOREIGN PATENTS OR APPLICATIONS [76] Inventor:

94,933 10/1957 Netherlands.....................73/D1G.2

Ivan J. Garshelis, 61 Oleander Way, Clark, NJ. 07066 July 12, 1974 Primary Examiner-Harold Broome I Attorney, Agent, or Firml-lubbell, Cohen, & Stiefel [22] Filed:

[21] Appl. No.: 488,220

[57] ABSTRACT A method and apparatus for circularly magnetizing a helical rod wherein an insulating sheath is placed over [52] US. Cl. 335/284; 29/602; 335/215;

the rod and a conductive sheath is placed over the insulation, the conductive sheath being in the form of a braided wire tube or the like. At one end of the rod, the rod and the tube are conductively connected. At the other end of the rod, the rod and the tube are both References Cited UNITED STATES PATENTS connected to a DC source to pass a direct current through the rod and the conductive tube.

2,878,447 3/1959 Price et 335/284 8 Claims, 1 Drawing Figure IIIIIIII.

U.S. Patent Dec. 16, 1975 This application is related to four other applications filed by me of even date, which otherapplications are entitled Magnetoelastic, Remanent, Hysteritic Devices,

Ser. No. 488,208, Electromagnetic Anisotropic Devices, Ser. No. 488,209, Electromechanical Transducer, Ser. No. 488,219, and Mechanical Magnet,'Ser. No. 488,841. The contents of these four applications are all hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a method for circularly magnetizing a helically coiled rod without distortion of the circular field.

SUMMARY OF THE INVENTION magnetization are employed. Generally speaking, to

circularly magnetize a magnetically remanent material such as a straight rod, all that need be done is to pass a direct current through the rod whereby to create the circular magnetization which thereafter persists by virtue of the magnetic remanence. However, if a rod is so circularly magnetized and is thereafter wound into a helical form, if the rod is magnetostrictive, the twisting or winding of the rod deforms the field out of circular which is undesirable for many of the applications mentioned in my copending applications. However, if the rod is first wound into a helix and then a current is passed therethrough, a perfect circular magnetization cannot be achieved due to the magnetic interaction of the circular fields in adjacent turns of the helically wound rod. This interaction also creates a distortion from a true circular field which is disadvantageous for the embodiments of the inventions described in the aforementioned co-pending applications.

To overcome these difficulties in accordance with the present invention, the rod to be circularly magnetized is first wound into a helical coil. Thereafter, an insulating tube, such as a piece of plastic spaghetti is slid over the helically wound rod or the rod may be dipped into an insulating lacquer or the like. After an insulating coating or layer has been placed on the helically wound rod, a flexible tubular conductor, such as a tubular piece of braided wire is slid over the insulating layer to surround the entire helical rod. At one end of the braided conductive outer sheath, a conductor is connected, the other end of which is connected to the corresponding end of the helically wound rod. At the other ends of the braided conductor and rod, a DC source is connected, whereby to cause a direct current to flow through the rod, through the conductive outer sheath, and then back to the DC source. As the direct current is flowing in one direction through the rod and the same current is flowing in the opposite direction through the braided sheath, the two oppositely directed 2 portions of the DC circuit are, generating the same amount of magnetic field but in opposite directions, whereby to cancel out all external field. Thus, there will be'no int'eraction between the fields of adjacent turns as there are noexternal fields to interact. Naturally, within the rod being magnetized, there is a circular field present. The external manifestation thereof is cancelled by theexternal field from the braided sheath.

BRIEF DESCRIPTION OF THE DRAWINGS The single FIGURE of the drawing is a view partly in elevation and partly schematic showing an apparatus for circularly magnetizing a helically wound rod.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the single drawing in detail, a con-- ductive rod which may, if necessary or desirable, be magnetostrictive, is first formed into a helix which will hereinafter be referred to as the helical rod 10 having opposite ends 12 and 13. Rod 10 may be solid or tubular. The outer surface of the helically wound rod 10 is. electrically insulated, either by sliding a flexible insulat-' ing tube such as a length of insulating plastic spaghetti 14 over the helical rod 10, as shown in the drawing, or by coating the exterior surface of the helically wound rod 10 with an insulating coating such as lacquer or the like as by dipping the rod into a 'hardenable bath of such insulating material.

After the helically wound rod 10 has been insulated, a suitable conductor is disposed on the outside of the rod. As shown in the drawing, a suitable conductor-is a flexible tube of braided conductive wire 16 of the same longitudinal extent as the rod 10, whereby the ends of the braided tube are essentially coincident with the ends 12 and 13 of the rod 10. If desired, in lieu of the braided conductive tube, the insulated helically wound rod 10 could have a conductor plated thereon over its insulating material to accomplish the same end. Moreover, the flexible tubular conductor 16 need not be made of braided wire, it could be of a metal filled flexible plastic tube or the like that is electrically conductive.

After the helically wound rod 10 has been insulated and then surrounded by a tubular conductor, electrical connections are made at the end 12 between the tubular conductor 16 and the end 12 of the rod 10 and electrical connections are made between a battery or other DC source 18 and the end of the rod 13 and the corresponding end of the conductive tube 16, preferably through a switch 20. Among potential DC sources are sources of AC, wherein a single one-half cycle of current is passed through the rod and tubular conductor.

When the switch 20 is closed a direct current passes through a circuit which may be traced from the positive terminal of the battery 18, through the flexible tubular conductor 16, through the electrical wire connection 17 through the helically wound rod 10 and then back to the negative terminal of the battery 18. The flow of the direct current will cause circular magnetization of the rod 10. However, that portion of the circular field produced by the current flowing through the rod 10 that is external to the rod will encounter the external circular magnetic field produced by the same direct current flowing in the opposite direction through the braided tube 16. As the amount of current in the rod 10 and the tube 16 are obviously the same, and as the current is flowing through the rod in an opposite direction to the current flow to the tube 16, then the external circular fields produced by the rod 10 and the tube 16 will be equal and opposite and will cancel one another out. Thus, while there is still an internal circular field within the rod 10, there is no external field from said rod nor from thesurrounding braided conductor, to interact with the field of an adjacent turn of the rod 10 and, hence, distort the field. This being the case, perfectly circular magnetization of the coiled rod will be achieved.

After the coiled rod has been circularly magnetized, the electrical connection can be broken, the braided tube 16 and the plastic spaghetti l4 removed and the rod may be incorporated in suitable devices. If the outer conductor has been plated on an insulating coating of the rod, then, depending on the application, it may be left or the plated outer conductor may be deplated.

While I have herein shown and described the preferred form of the present invention and have suggested modifications thereof, other changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of this invention.

What is claimed is:

1. A method for circularly magnetizing a helical conductive rod comprising the steps of:

forming the conductive rod into a helix;

enveloping the outer surface of said helical rod with an electrical insulator;

enveloping said electrical insulator with a tubular conductor;

electrically connecting one end of said tubular conductor to the corresponding end of said helical rod;

and electrically connecting the other ends of said coiled rod and said tubular conductor to a dc.

source;

2. The method of claim 1, wherein the outer surface of said helical rod is enveloped with an electrical insulator by sliding a flexible insulating tube onto said coiled rod.

3. The method of claim 1, wherein said electrical insulator is enveloped by a tubular conductor by sliding a flexible braided wire tube over said insulator.

4. The method of claim 2, wherein said electrical insulator is enveloped by a tubular conductor by sliding a flexible braided wire tube over said insulator.

5. A method of claim 1, wherein the outer surface of said helical rod is enveloped with an electrical insulator by said helical rod with a dryable liquid insulating coatmg.

6. The method of claim 1, wherein said electrical insulator is enveloped by a tubular conductor by plating a conductive tube over said enveloping insulator.

7. The method of claim 4, wherein said helical rod is magnetostrictive.

8. Apparatus for circularly magnetizing a helically wound conductive rod, comprising:

said helically wound conductive rod;

an insulator in enveloping relation with said rod;

a tubular conductor in enveloping relation with said insulator;

a conductor connecting one end of said tubular conductor to the corresponding end of said helical rod; and

conductive means for connecting the other end of said tubular conductor and said rod to the opposite tenninals of a dc source. 

1. A method for circularly magnetizing a helical conductive rod comprising the steps of: forming the conductive rod into a helix; enveloping the outer surface of said helical rod with an electrical insulator; enveloping said electrical insulator with a tubular conductor; electrically connecting one end of said tubular conductor to the corresponding end of said helical rod; and electrically connecting the other ends of said coiled rod and said tubular conductor to a d.c. source.
 2. The method of claim 1, wherein the outer surface of said helical rod is enveloped with an electrical insulator by sliding a flexible insulating tube onto said coiled rod.
 3. The method of claim 1, wherein said electrical insulator is enveloped by a tubular conductor by sliding a flexible braided wire tube over said insulator.
 4. The method of claim 2, wherein said electrical insulator is enveloped by a tubular conductor by sliding a flexible braided wire tube over said insulator.
 5. A method of claim 1, wherein the outer surface of said helical rod is enveloped with an electrical insulator by said helical rod with a dryable liquid insulating coating.
 6. The method of claim 1, wherein said electrical insulator is enveloped by a tubular conductor by plating a conductive tube over said enveloping insulator.
 7. The method of claim 4, wherein said helical rod is magnetostrictive.
 8. Apparatus for circularly magnetizing a helically wound conductive rod, comprising: said helically wound conductive rod; an insulator in enveloping relation with said rod; a tubular conductor in enveloping relation with said insulator; a conductor connecting one end of said tubular conductor to the corresponding end of said helical rod; and conductive means for connecting the other end of said tubular conductor and said rod to the opposite terminals of a dc source. 